A liquid crystal projector modulates light by liquid crystal light valves and projects an image onto a screen. In order to effectively use irradiating light from a light source, a polarized light generator is typically included to unify the irradiating light into s-polarized light or p-polarized light and to enter the polarized light into the liquid crystal light valves, as disclosed in JP1996-304739A, for example. For example, a polarized light generator that generates s-polarized light includes: a plurality of polarization separating layers that separate irradiating light into s-polarized light and p-polarized light; a plurality of reflecting layers that reflect the separated s-polarized light or p-polarized light; and a phase plate layer that converts the separated p-polarized light into s-polarized light. In typical, the polarization separating layers and the reflecting layers are arranged alternately and parallel to one another, and the phase plate layer is disposed corresponding to the polarization separating layers or the reflecting layers. Furthermore, since no desired polarized light can be obtained if the light enters directly into the reflecting layers, the polarized light generator generally includes a light shielding plate that shields the light entering the reflecting layers, as disclosed in WO 97/50012, for example. The light shielding plate is disposed at a light incident side of the polarized light generator, and is a plate-like member that has light shielding portions corresponding to the reflecting layers and opening portions corresponding to the polarization separating layers.
The polarized light generator of such a structure is used in combination with a so-called integrator optical system that divides a light beam from the light source into a plurality of partial light beams and superposes them on the liquid crystal light valves. In this case, the light from the light source is divided into a plurality of partial light beams and the obtained partial light beams converge toward the polarization separating layers. In other words, the light enters the polarization separating portions in a state of being converged onto the opening portions of the light shielding plate. Accordingly, only approximately 5% of the light is shielded by the light shielding plate.
The light shielding member generates heat when it shields the light. The heat may possibly subject the polarized light generator and thus the phase plate layer disposed thereon to high temperatures. Since the phase plate layer is generally composed of organic matters, subjecting it to high temperatures may possibly cause a decrease in a useful life of the layer.